This invention is directed to a liquid detergent which contains a stabilized silicate. More particularly, the invention relates to builder free liquid detergent formulations which include a mixture of a synthetic inorganic soluble alkali silicate and an anionic siliconate.
Solid detergent formulations are sold in powder or granular form. A disadvantage of solid detergents is that, on account of the hygroscopicity of individual raw materials of the formulation, the solid detergent shows a pronounced tendency towards caking or clumping in the presence of small quantities of moisture. This does not make the detergent unusable, however, because the effect of the individual components of the detergent remain intact even after clumping or caking in the presence of moisture. However, the appearance of the detergent in most cases is diminished. As a result, there has been a desire to develop liquid detergent compositions for use in lieu of conventionally formulated solid detergent compositions. The liquid detergent allows for use of lower washing temperatures inclusive of cold water laundering. Granular detergents have not fully adapted to such variations because of weaknesses in respect of dissolving speed, insolubility, and cleaning efficiency. Due to such problems of caking and the slowness of solid and granular detergents to dissolve, trends in detergent manufacture have leaned toward the liquid detergent. Such detergents usually include an organic surfactant, water, various detergent builder systems, enzymes, bleaches, pH modifiers, softeners, and solvents. It is not uncommon to also include an antifoam or defoamer formulation as part of the detergent package.
Soluble silicates have always been an important raw material in the manufacture of detergents. Various tests of silicates in detergents conclude that soluble silicates improve detergency. However, developments of new forms of liquid detergents with neutral pH's and concentrated detergents have affected the use of silicates. Modern detergents, including liquid detergents, are complex mixtures of ingredients optimized for beneficial cleaning activity at low cost while minimizing the objectionable features of individual components. Commercial liquid detergent systems are primarily nonionic and/or anionic neutral surfactant systems. When soluble silicates are used however, undesirable effects such as gel formation, liquid phase separation, precipitation formation, and incompatability occur, and thus prevent silicate use in liquid detergents. The present invention however provides for the addition of anionic siliconates to alkali silicate solutions, to provide stable solutions that resist precipitation/gelation when neutralized or acidified. These stabilized silicate solutions, after adjusting the pH to optimized levels, can be added to any liquid detergent formulation and will remain completely compatible and stable.